The invention relates to a toggle clamping device for use in car bodywork construction in the motor vehicle industry.
The present invention relates to a toggle clamping device or piston-cylinder unit in which, when in the installed condition, the opening angle of a clamping arm, the final position of an interrogator device and the final position of a damping device can all be adjusted and locked simultaneously and jointly through a single adjusting element from outside of the toggle clamping device. The adjusting can be accomplished without dismantling the toggle clamping device.
There is shown in U.S. Pat. No. 5,845,897 a toggle clamping device for car bodywork construction having a rectangular grip holder having a cross-section guided orthogonally in relation to the longitudinal axis of the piston rod and being constructed from two housing sections, and with a cylinder attached in axial extension to the cylinder-side end of the grip holder. U.S. Pat. No. 5,845,897 is hereby, included by reference, as a part of this specification. In U.S. Pat. No. 5,845,897, the piston which is to be acted upon alternately on both sides by pressure-medium pressure, in particular air pressure, is guided in a longitudinally displaceable and sealing manner, and extends through the cylinder and a hollow space of the grip holder with its piston rod in the axial direction. A toggle joint arrangement with a clamping arm coupled thereto is fixedly connected at the free end of the piston rod. Limit switches, pneumatic switches and sensors are integrated within a space in the grip holder. The switches are adjustable relative to one another and are arranged and fixed to a mount forming a cover and serve as an interchangeable interrogator cassette in the form of a printed circuit in way of a slot that extends in the axial direction of the grip holder. The interrogator cassette, in top plan view, has a T-shaped configuration including an attachment rail and a flange that is linked to a section of the piston rod. The interrogator cassette is plugged in through a narrow slot extending in the direction of the piston rod from the back of the housing of the grip holder. This arrangement permits the toggle clamping device to be attached from all four sides from the back in such a manner that the section will seal the slot joint-tight towards the outside. The section can be designed in an L-shaped configuration in a cross-section guided orthogonally in relation to the longitudinal axis of the piston rod. The land of the "L" is parallel with the longitudinal axis of the piston rod and has switches as adjustable versions, while the crossbar closes the slot towards the outside. A further embodiment is provided with a grip holder consisting of two dish-shaped housing sections lying flush on top of each other and encasing the toggle joint arrangement. The piston rod and the limit switches are provided in a dirt and dust proof manner towards the outside. The dish-shaped housing sections feature the slot for arranging the interrogator cassette on the one, i.e., the narrower side, of the grip holder that has a rectangular cross-section. The section can plunge into the slot to such an extent that the one, i.e., the narrower side of the grip holder having a rectangular cross-section, surmounts the boundary of the L-shaped section which is pointing towards the outside. This toggle clamping device is equipped with a limit stop for the toggle joint arrangement, primarily in the above-dead-center position of the toggle joint, the limit stop being designed as a stop which is adjustable in the direction of its longitudinal axis to be actuated upon from the outside as a crew cap. For toggle clamping devices, operating with this so-called cassette technique, the interrogator cassette is plugged into the housing from the rear of the clamp housing through a narrow, slot-shaped openings. This construction results in very low service demands, since, for instance, by loosening just one screw it is possible to interchange the complete interrogator cassette that have a switch and plug which are completely cabled in themselves. Therefore, a completely interchangeable stock of interrogator cassettes can be available. This ensures minimum downtimes in the event that the case the interrogator cassette should have to be changed. It is also possible to quickly adjust interrogator cassettes for certain strokes and/or opening angles for replacement with build-in interrogator cassettes.
There is disclosed in EP 0 778 107 A1 a toggle clamping device for use in car bodywork construction in the motor vehicle industry, with a grip holder and a cylinder attached thereto in axial extension, in which a piston to be acted upon alternately on both sides by the pressure-medium, preferably air pressure, is guided in a longitudinally displaceable and sealing manner and extends through the cylinder and the grip holder with its piston rod. A toggle joint is arranged with an associated clamping arm within the housing of the grip holder at the free end of the piston rod. The piston subdivides the cylinder into a cylinder return stroke chamber and into a cylinder clamping stroke chamber. The cylinder clamping stroke chamber is closed in a sealing manner on the front end side by a cover to which a damping device for braking the opening movement of the piston is allocated. The cylinder return stroke chamber and the cylinder clamping stroke chamber are either alternately connected to the pressure-means source or vented through a one each connection duct. The connection duct functions to relieve the cylinder clamping chamber or to be connected with the pressure-medium source being shut off from the cylinder clamping chamber starting from a certain opening stroke of the piston, whereupon the cylinder clamping chamber is vented only via a throttle device. The damping device is controlled or adjustable. This reference suggest designing the damping device as a function of the opening angle of the clamping arm, preferably in an infinitely variable and, particularly in a longitudinally adjustable manner. This is accomplished by a machining operation. This makes it possible to adjust the throttle device depending on the operating conditions so that a particularly sensitive and accurate damping effect can be achieved. To enable final position damping over a larger range of an angle of swing from 0 to 125.degree., the damping device is designed to be longitudinally variable and lockable in its axial extension in relation to the piston. The throttle device can be varied depending on the desired angle of swing of the clamping arm either by continuous or other variation of the axial length of the throttle body. In one embodiment of this reference, this can be done by the supporting piston having a projection on the front side facing the piston which is longitudinally adjustable depending on the desired angle of swing. This longitudinally adjustability can be achieved in an infinitely variable manner, however, also by removal of material, for instance by covering the projection in order to achieve the desired damping effect depending on the angle of swing of the clamping arm. The damping body can consist of two or several parts which are telescopically adjustable within each other. These parts can be connected with each other, for example, by screw threads. Furthermore, it is also disclosed in this reference that the length can be adjusted hydraulically, for instance by corresponding stroke adjustment of a piston in a cylinder, thereby accommodating the respectively desired angle of swing of the arm and achieving the respectively desired damping effect.
A toggle clamping device is disclosed in DE 42 42 601 A1 that includes a piston-cylinder arrangement in which the piston and piston rod are guided in the cylinder and are displaceable between two final position limiting elements by being acted upon by the pressure medium. At least one of the two final position having limiting elements that are adjustable in the axial direction within the cylinder, and at least one final position limiting element being held in a torsion-proof manner within the cylinder and adjustable by a spindle supported at the cylinder. This spindle is configured as a threaded spindle in certain areas and extends through a threaded bore of the one final position limiting element into a corresponding opening of the piston rod. The spindle can be turned by means of a hand-wheel arranged on the front side of the cylinder. The respective final position limiting element is arranged in a corresponding counter-thread for longitudinal adjustment by means of a male or female thread. Switches for control of the piston-cylinder arrangement are adjusted simultaneous with the adjustment of the respective final position limiting element. As a result of the one final position limiting element being displaceable in axial direction within the cylinder, an infinitely variable adjustment of the length of stroke of the piston rod according to the respective requirements can be achieved. Adjustment of the final position limiting element is affected by means of a spindle supported at the outer housing cover of the cylinder and extending through a tapped hole of the final position limiting element into a corresponding opening of the piston rod.
Also, there is disclosed in DE 91 04 532.01 U1 a toggle clamping device for car bodywork construction that includes a grip holder and a cylinder attached thereto in axial extension, in which a piston to be acted upon alternately on both sides by pressure-medium pressure by air pressure. In this reference the piston rod extends through the cylinder and the grip holder in the axial direction and is guided in a longitudinally and sealing manner. A toggle joint arrangement is coupled with a clamping arm at the free end of the piston rod. Limit switches including plugs for feeding current to the limit switches are provided. The plugs are arranged at different positions on the toggle clamping device, with
(a) a prismatic connecting body, to which the plug which is an angle plug is connected, and arranged in a corner recess of the cylinder and/or of the bottom cover; PA1 (b) the prismatic connecting body has a threaded bore with which the angle plug is coupled; PA1 (c) the prismatic connecting body has an interior space to which the threaded bore is connected, the electric leads leading into the interior space; PA1 (d) the prismatic connecting body being arranged in several--preferably in three--mounting positions deviating from each other by 90.degree. and is detachably locked in the corner recess.
There is disclosed in DE 91 05 755.8 U1 a clamping device consisting of a headpiece with a mechanical adjusting device for the clamping lever and an actuating cylinder for the mechanical adjusting device attached to the headpiece by means of armature bars. An adjustable final position interrogator elements being arranged in the actuating cylinder which has allocated to it a final position transmitter which is in work connection with the piston rod and whose cables are carried to the cylinder end. The final position interrogator elements, such as micro-switches, are arranged on stirrup-type supports which are adjustably and are fixed to two adjoining armature bars.
The UK Patent No. 1,413,751 relates to a pressure medium actuated toggle clamping device for body parts, consisting of a housing with a cylinder chamber for the piston, at the free piston rod end. Guide means for the piston rod and a piston rod pin are connected through a strap with the toggle joint of a work clamping end angle lever. The cylinder return stroke chamber and the cylinder clamping stroke chamber can alternately be connected to either the pressure-means source or vented via one each connection duct. The piston subdivides the cylinder into a cylinder return stroke chamber and into a cylinder clamping stroke chamber. The cylinder return stroke chamber and the cylinder clamping stroke chamber can alternately be connected to either the pressure-means source or vented via one each connection duct. Furthermore, the cylinder clamping stroke chamber is closed in a sealing manner by a cover on the back end side to which a damping device for braking the opening movement of the piston is allocated.
The work clamping end angle lever is swivel mounted on a journal supported in the housing. The guide means for the piston rod consist of the ends of the piston rod pin and the guide grooves arranged in the housing that extend in the axial direction of the piston rod. In addition, a stroke limiting stop or buffer is arranged at the bottom of the cylinder chamber which is infinitely axially adjustable from outside by means of an adjusting screw. Furthermore, the toggle clamping device is characterized in that the housing carries a fixing eye and is supported on a pivot pin to enable the housing to be pivoted when moving the piston and piston rod. The housing can be maintained stationary in any position. Furthermore, the arrangement makes it possible to position the housing so as to be movable about a center of rotation. The center of rotation can be on the side with the cylinder chamber so that the housing can be swiveled. This offers the advantage that the housing can be moved towards and/or away from the work during the clamping operation. Depending on the respective requirements, the axial movements of the piston and of the piston rod can also be performed simultaneous with the movement of the housing. A characteristic feature of this reference is that the working range of the angle lever is infinitely variable, at option, by the infinitely variable stroke of the piston. It is possible to move the angle lever within a working rang of up to 180.degree.. The piston rod is always safely movable from its final position without requiring any special effort even if the angle lever has been pivoted all the way into its zero or dead position. The buffer at the bottom is a buffer consisting of for example rubber.